1. Field of the Invention
The present invention relates to an imaging device provided with a plurality of optical systems having parallax with each other.
2. Description of the Related Art
According to Japanese Patent No. 4177826, a parallax distribution (a histogram) is generated from first and second images by extracting feature points and detecting their corresponding points. Based on the distribution, a moving object is detected.
According to Japanese Patent Application Laid-Open No. 07-95623, focus of each of left and right imaging lenses is controlled by an auto focus (AF) drive circuit. Output from a CCD is written in a memory for electronic zooming. A microcomputer controls a clipping position of a clipping frame for electronic zooming according to AF data proportional to a subject distance. Thereby, a convergence angle is electronically controlled.
In a stereoscopic imaging device provided with a pair of left and right imaging optical systems (or provided with two cameras), an amount of parallax generated between left and right images needs to be adequately adjusted to stereoscopically display the obtained parallax images appropriately. Particularly, for a subject which a photographer intends to photograph as a main subject, it is desirable that an amount of parallax is adjusted to be adequate to reduce too much protrusion and retreat in a stereoscopic image. Conventionally, an amount of parallax has been adjusted by controlling spacing between a pair of imaging optical systems, a distance to the point of intersection of the optical axes (a convergence point), and a convergence angle. However, this adjustment requires the imaging optical systems to be driven mechanically, causing a problem that a structure and controls of the camera are complicated.
According to the technology of Japanese Patent Application Laid-Open No. 07-95623, when an inexpensive lens is used, it is difficult to precisely calculate an actual subject distance by using focus information because of influence of, for example, thermal characteristics, causing an error in adjustment of a convergence angle based on the focal length.